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Tideway Tunnel aims to ease pressure on London's sewers

Thames Water says currently sewage flushes into the Thames in heavy rainfall Photo: ITV News

Thames Water has today refuted claims by the former Ofwat chief that the company's plans for a 'super sewer' are overpriced.

The company has hit back, saying all other suggested options would cost more, and the new network is desperately needed to ease pressure on the current system, which was built for a much smaller population.

The new system has been designed to ease pressure on London's 1850s sewers Credit: ITV News

*Thames Water says: *

The Thames Tideway Tunnel is needed to give greater capacity to a system built in the 1850s to take both sewage and rainwater. London's population growth and the covering over of open land which could once absorb rainfall mean that a system designed to discharge to the river only occasionally, after exceptionally heavy rainfall, now discharges untreated sewage to the river on average once a week.

"In-depth studies have shown all of the suggestedalternatives to the tunnel would take longer, cost more, cause much moredisruption and fail to clean up the river properly.

“Sir Ian claims groundwater infiltration to the sewers isthe main problem. It's not. If it were, overflows to the riverwould occur whenever groundwater levels are high. But they don't. Overflows take place only straight after rainfall. That's because thehard surfaces in London cause more run-off than the sewers can hold. London has outgrown its legacy sewer system. That is why we need thetunnel."

– Thames Water

Thames Water also stressed the company hasn't asked the Government for a loan to for the works. It says the company is funding and delivering £2.7bn of it's £5.4bn programme to clean up the Thames as 'business as usual'.